Vane wheels of the type initially mentioned are used, for example, in stationary gas turbines as moving vane wheels which are arranged downstream of a combustion chamber of the gas turbine in the direction of flow of fuel gas and are exposed to high temperatures there. The cooling of the vane leaves and, in particular, of the vane feet of such gas turbine vanes subjected to high temperature loads is particularly involved because of the complicated cooling fluid routing required for this purpose and the difficult sealing-off work, along with the high centrifugal force load. In turbine moving vanes, at the present time, convective cooling and other measures for reinforcing the heat transition between a cooling fluid flowing through cooling channels on the vane foot and the vane foot are adopted. Often, only a comparatively small quantity of cooling fluid is available, so that only a low heat flow can be discharged through a platform of the vane foot. The platform surface temperature can consequently be lowered only slightly.
For this purpose, US 2004/0081556 A1 discloses a gas turbine vane with a vane foot, a platform and a vane leaf. The platform extends from an inflow-side edge to an outflow-side edge with respect to the hot gas which flows through the gas turbine in the axial direction. The platform has an outflow-side edge which runs in the circumferential direction of the turbine disk and which projects beyond the axial width of the turbine disk in the manner of roof eaves. On the underside of the outflow-side edge of the platform are provided a plurality of structural elements influencing the cooling air flow. Guide ribs corotating rapidly with the rotor move over the more or less stationary cooling air and cause a flow deflection of the cooling air from the circumferential direction into the axial direction. Moreover, on the underside of the platform, both a turbulator-like local plinth field and ribs extending in the axial direction are provided. The plinth field and the ribs locally increase the heat transition from the outflow-side edge of the platform into the cooling air flowing past on the underside.